In Europe, eggs of the Common Cuckoo (Cuculus canorus) have been found in more than 125 different host species. However, very few species are frequently parasitized. The Cuckoo is divided into several distinct races t...In Europe, eggs of the Common Cuckoo (Cuculus canorus) have been found in more than 125 different host species. However, very few species are frequently parasitized. The Cuckoo is divided into several distinct races termed gentes. Females of each gens specialize in parasitizing a particular host species. More than 20 such gentes are recognized in Europe. Each female Cuckoo lays eggs of constant appearance. Most gentes can be separated based on their distinct egg types, which in many cases mimic those of their hosts. Different gentes may occur in sympatry or may be separated geographically. Some gentes may occur in restricted parts of the host’s distribution area. These patterns raise some fundamental questions like: Why are some passerine species preferred as hosts while others are not? Why does a host population consist of individuals either accepting or rejecting Cuckoo eggs? Why is there marked variation in egg rejection behavior between various host populations? How distinct and host-specialized are Cuckoo gentes? These questions are discussed in relation to existing knowledge and future perspectives.展开更多
It was shown by Formanek and Sibley that the group determined characterizes a finite groupG up to isomorphism. Hoehnke and Johnson (independelltly the suthors--using an argumentof Manslield) showed the corresponding r...It was shown by Formanek and Sibley that the group determined characterizes a finite groupG up to isomorphism. Hoehnke and Johnson (independelltly the suthors--using an argumentof Manslield) showed the corresponding result for k-characters, k = 1, 2, 3. The notion of kcharacters dates back to nobenius. They are determined by the group doterminaDt and maybe derived from the character table CT(G) provided one knows additionally the functionswhere C(C) = {Cg, g E G} denotes the set of conjugacy classes of G.The object of the paper is to present criteria for finite groups (more precisely for solublegroups G and H which are both semi-direct products of a similar type) when1. G and H have isomorphic spectral tables (i.e., they form a Brauer pair),2. G and H have isomorphic table of marks (in particular the Burnside rings are isomorphic),3. G and H have the same 2-characters.Using this the authors construct two non-iS.Omorphic soluble groups for which all these threerepresent at iont heor et ical invar taut s coincide.展开更多
文摘In Europe, eggs of the Common Cuckoo (Cuculus canorus) have been found in more than 125 different host species. However, very few species are frequently parasitized. The Cuckoo is divided into several distinct races termed gentes. Females of each gens specialize in parasitizing a particular host species. More than 20 such gentes are recognized in Europe. Each female Cuckoo lays eggs of constant appearance. Most gentes can be separated based on their distinct egg types, which in many cases mimic those of their hosts. Different gentes may occur in sympatry or may be separated geographically. Some gentes may occur in restricted parts of the host’s distribution area. These patterns raise some fundamental questions like: Why are some passerine species preferred as hosts while others are not? Why does a host population consist of individuals either accepting or rejecting Cuckoo eggs? Why is there marked variation in egg rejection behavior between various host populations? How distinct and host-specialized are Cuckoo gentes? These questions are discussed in relation to existing knowledge and future perspectives.
文摘It was shown by Formanek and Sibley that the group determined characterizes a finite groupG up to isomorphism. Hoehnke and Johnson (independelltly the suthors--using an argumentof Manslield) showed the corresponding result for k-characters, k = 1, 2, 3. The notion of kcharacters dates back to nobenius. They are determined by the group doterminaDt and maybe derived from the character table CT(G) provided one knows additionally the functionswhere C(C) = {Cg, g E G} denotes the set of conjugacy classes of G.The object of the paper is to present criteria for finite groups (more precisely for solublegroups G and H which are both semi-direct products of a similar type) when1. G and H have isomorphic spectral tables (i.e., they form a Brauer pair),2. G and H have isomorphic table of marks (in particular the Burnside rings are isomorphic),3. G and H have the same 2-characters.Using this the authors construct two non-iS.Omorphic soluble groups for which all these threerepresent at iont heor et ical invar taut s coincide.
